Method of truing the teeth of saw blades



Feb. 9, 1932. L. T. MEDHOLDT 1,844,225.

METHOD OF TRUING THE TEETH OF SAW BLADES Original Filed Aug. 8. 1927 gym/1%,

Patented Feb. 9, 1932 LOUIS T. MEDHOLDT, F ROCKFORD, ILLINOIS, ASSIG-NOR TO MATTISON MACHINE WORKS, OF ROCKFORD, ILLINOIS, A CORPORATION OF ILLINOIS METHOD OF TRUING THE TEETH OF SAW BLADES Original application filed August 8, 1927, Seria! No. 211,303.

Divided and this application filed February 3, 1930. Serial N0. 425,693.

The invention relates generally to the art of sawing andmore particularly to an improved method of truing the teeth of saw blades.

The invention contemplates primarily the truing of the teeth of saws of a circular blade type suchas those commonly used in rippers or jointers, wherein lumber is ripped or jointed for glueing purposes. In such machines it is desirable to have the out edges so perfect that two or more of the pieces, after passing through the machine, may be successfully glued without further finishing.

To obtain so accurate a cut it is essential not only to provide the machine'with a proper mounting for the saw blade and ei'hcient means for feeding the work through the machine in a straight line, but also to obtain saw blades with teeth which will out uniformly.

For the purpose of obtaining such uniform teeth, it has been the practice to true the teeth of the saw blade while the blade is running at normal speed so that the corresponding cutting edges of the different teeth are in peripheral alinement. This operation is known generally in the art as jointing the saw teeth. Generally the dressing of the teeth has been accomplished by positioning an abrasive element with a surface parallel to the side-edges of the teeth of the saw then moving the element perpendicularly to the saw blade and into contact with the sides of the saw teeth. This method, however, has caused the abrasive element to be notched at the point where it contacts the tips, of the saw teeth and not only has made it necessary to renew the element frequently but has caused improper jointing of the teeth.

The general object of the invention is to provide a new and improved method of truing saw blades which avoids the tendency of the saw teeth to gouge and break away the alarm sive element so that the teeth of the saw blade may be peripherally alined with greater accuracy than hasbeen heretofore obtainable. A further object is to provide an improved method of truing saw'teeth whereby an abrasive element is moved into engagement with the sides of the teeth by movement outwardly from and substantially radiallyiwith respect to the saw axis.

For the purpose of illustrating more clearly the practice of my invention, 1 have illustrated an apparatus adapted to utilize the new method, but it is to be understood that the form of the apparatus may be varied at will without departing from the spirit and scope of the invention as expressed in the claims.

in the drawings:

Figure l is a fragmenta'l elevational view of a machine adapted to the present invention.

Fig. 2 is a fragmental plan view of the machine shown in Fig. 1. 1

- Fig. 3 is an end elevational view of the tool arm as viewed from the right in Fig. 2, the saw blade being shown in section.

Fig. 4 is a sectional view of a saw blade of the swaged tooth type illustratingsomewhat diagrammatically the various positions of the abrasive element in the practice of the present method.

' In the drawings, a fragment-a1 portion of a rip saw or jointer is shown of the type wherein the saw blade is mount d on an arbor which overhangs the work table. A portion (3 of the main frame (not shown) projects above the work table (not shown) and rotatably sup ports a horizontal saw arbor so that it pro-; jects over the work table. Upon the arbor 7 a saw blade 9 is mounted so as to be positioned directly above the feed chain or other work advancing means (not shown). The saw blade 9 is provided with a guard in the form of a housing having similar sections 10 (only one herein shown) mounted on the portion 6 of the frame so that they may be separated longitudinally of the machine to expose the saw 9.

For the purpose of truing the saw teeth, a bracket 14: is attached to the housing 10 to support an arm 15 pivotally mounted in the bracket and carrying a member 16 at its outer end. The member 16 is adjustably mounted on the free end of the arm 15 and is arranged to support abrasive elements 1?.

As shown in Fig. 2, the bracket M has a pair of lip-standing lugs spaced laterally of the housing and having bearings therein to receive a pivot for the arm 15. The pivot as i herein shown comprises a shaft 2-1 rotatably mounted in the bearings in the lugs 20 and engaging two laterally spaced lugs 22 on the end of the arm 15. The shaft 21 and the lugs 22 are in screw threaded engagement with each other so that the arm 15 may be adjusted laterally of the saw blade by turning a knurled handle 24; fixed on the end or" the shaft 21. Thebracketl is preferably positioned so that the arm15,.when swung about its pivot 21, moves the abrasive element 17 substantially radially of the sawblade 9. The member 16 is preferably mounted for adjustment transversely of the arm'15 on ways 25 and may be secured in position by means of a thumb screw 26.

The arm 15 is adapted, during normal operation oi. themachine, tobe swung back from the operative position shown in fulllines in Fig. .1 to the inoperative position shown in dotted lines. When the arm is in its operative position adjacent to the saw 9, it is held against downward movement by an adjusting screw 27 carried by thearm 15 and engaging a lug 28 extending fromthe housing section 10. The screw 27 is used-t0 obtain feeding movement of the abrasive elements substantially radially of thesawv 9.

The member 16 is adapted to receive a plu rality of abrasive elements, in the present case three,.two of which .are the elements 17 adapted to be'brought into operative engagement-with the opposite sides of the saw teeth and the other .of whichIis a centrally positioned element, 17 which may be brought into engagement with the peripheral or top edges o't'the teeth. The elements 17 and 17. are secured to the member 16 .for individual adjustment by means of. a plate 29-whichis attached to the member 16 by screws 30.

Inthe practice ofmy improved method,

the corners of the saw teeth arepreferably brought into peripheralalinement by first jointingthe peripheral or topedges of the teeth so that all pointsthereon are equi-distant from the axis of the saw and then successively dressing the sides of the teeth until allio'f the teeth become uniform.

The jointing of the outer peripheral surface of the teeth is accomplished by moving the abrasive element .17 substantially.radially of the saw 9 into contact with theteeth.

In dressingthe sides ofithe teeth, oneofthe elements 17 is first adjusted to the proper angle andmay then be moved from a position A (Fig. 4c) laterally of the saw 9 until the corner of the element 17 contacts the side ofthe-saw. as shown in position Br The element is then movedsubstantially radially'ot the saw to position C. During the latterpart of the'movement ofthe element 17 from position Bto position 0, the sides ofthe teeth willbe dressed so thatthe tips of theteeth will be peripherally alined.

It is, of course,'to be understood that my screw in any adjusted position, a nut '82. may bepositioned .on the screws.

To dress the side edges of the teeth, the arm 15 is-firstadjusted by means of the screw 27 so that the element 17 clears the teeth and so that when "the arm is moved laterally by means ofthe pivot screw 21 an abrasive element 17 is moved from a position corresponding to A of Fig. 41 to that corresponding toB. In. this B position, the adv'ancetipof the abrasive element may contact thesaw blade, the edge of the abrasive element adjacentthe sides ofthe teethbeingparallelto the said. sides. 'By manipulating the thumb screw 27.to swing. thearm ,15- outwardly of the saw, the abrasive element islfedfintoa position corresponding with-that designated Gin Fig. ftwherein it engages and dresses the sides ofthe saw teeth. This procedure, may then be repeated to dress the opposite. side edges of the teeth by means oftheother abra-- sive element .17. p

It'is believed apparentthat-by feedingthe abrasive element outwardly fromthe aXisof the saw when dressing the sides of the teeth there is no tenclency.for thetip of. the teeth to gouge into the element such as is present if the element is fed laterally into engagement with the side. edges. By truing the. top edges and also the sideedges ,while the saw blade is..operating at its normal speed, the teeth becomeproperly jointed sothat they will cut uniformly.

This application isa division ofmy application No..21l,303, filed'August 8, 1927.

I claimas my invention: j

1. The method of lressing sawblade teeth which consists in moving an. abrasive element laterally .into contact with the side of the blade inwardly of the teeth. then movingsaid element outwardly along the sideofthe saw into engagement withthe inclined sides of" the teeth with the contacting surfacesof the abrasive element and teeth parallel, and etfooting relative rotary niotion-between the p blade and said element.

2. The method of dressing the angularly' disposed sides of theiteeth of arotating-saw which consists infeeding an abrasive element parallel to the'body ot the rotating saw into contact with-saidsides of the "teeth.

3. The method of dressing the angularly disposed sides ofthe' teeth of a rotary saw which consists'in positioning. an abrasiveelement adjacentxto-the side=of1thesaw with one edge of the-abrasive substantiallyzparallel to the sidesof the :teeth .and positioned rat an angle to the saw which equals the angle to which the saw teeth are to be dressed, and moving the abrasive substantially radially outwardly of said saw blade in a plane parallel to said blade into contact with the teeth While the angular relation of the saw and abrasive is maintained so as to dress the sides of the teeth to the desired angle.

In testimony whereof, I have hereunto affixed my signature.

LOUIS T. MEDHOLDT.

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